Police find gun in search for Croydon robber

Police who are hunting for a man involved in an armed hold-up in Croydon in Melbourne's east have found a gun they think might have been used in the robbery.

Two masked men stole cash from a gaming venue in Dorset Road just before 10:00am this morning.

Police arrived as the robbers were leaving, and chased and arrested one of them.

Officers have been door-knocking and using the dog squad and a helicopter to try to find the other man.

They found the gun on Mount Dandenong Road at 3:15pm this afternoon.

Superintendent Graeme Arthur says the wanted man is dangerous and should not be approached.

"He could lay low for a number of hours," he said.

"All we can do is do a house to house search in the area that we have blocked off and hope for the best.

"The difficulty is that there are a number of people away on holidays, a number of people still at work, so we are concerned that someone might come home, find him in the yard, so we are relying on people to contact us."